Here is how to solve this if Excel opens up blank when you double click an Excel attachment in Outlook 2007/2010

1.Close the message.2.Start Excel.3.Click the Microsoft Office Logo Button, click Excel Options and then click Advanced.4.Under the General tab, click to clear the Ignore other applications that use Dynamic Data Exchange (DDE) option, then click OK.5.Exit Excel.

Go back to Outlook and double click the Excel attachment. It should now work.